FUEL INJECTION SYSTEM TROUBLESHOOTING
SERVICE MANUAL NUMBER 23
Page 5D-32
90-861326--1 MARCH 1999
Backfire Symptom (Continued)
12
1. Check for intermittent opens or short
to grounds in the MAP sensor and
TP sensor circuits. Also check for
throttle linkage sticking, binding or
worn.
2. An intermittent failure may not store
a DTC.
3. If a problem is found, repair as nec-
essary.
Was a problem found?
-
Go to OBD
System
Check
Go to Step 13
13
1. Check engine mechanical for the fol-
lowing conditions:
•
Low compression.
•
Sticking or leaking valves.
•
Worn camshaft lobe(s).
•
Incorrect valve timing.
2. If a problem is found, repair as nec-
essary.
Was a problem found?
-
Go to OBD
System
Check
Go to Step 14
14
1. Check Intake and exhaust man-
ifold(s) for casting flash.
2. If a problem is found, repair as nec-
essary.
Was a problem found?
-
Go to OBD
System
Check
Go to Step 15
15
1. Review all diagnostic procedures
within this table.
2. If all procedures have been com-
pleted and no malfunctions have
been found, review/inspect the fol-
lowing:
•
Visual/physical inspection.
•
Scan tool data.
•
All electrical connections within a
suspected circuit and/or system.
3. If a problem is found, repair as nec-
essary.
Was a problem found?
-
Go to OBD
System
Check
Contact
MerCruiser
Customer
Service
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